1. Field of the Invention
The present invention relates to a recording or reproducing apparatus which has a rotary drum unit and which is arranged to record or reproduce a signal by using a tape.
2. Description of the Related Art
As one conventional example of this kind of recording or reproducing apparatus, a video tape recorder or the like is known which is arranged to carry out recording or reproduction of a signal while keeping a magnetic tape wrapped around a rotary drum unit equipped with a magnetic head by a predetermined angle such as about 180 degrees or about 360 degrees. In general, the rotary drum unit includes a rotating upper cylinder and a stationary lower cylinder, and the upper cylinder is provided with a pair of magnetic heads which are spaced apart by, for example, 180 degrees. Connection between the magnetic heads and an external electronic circuit is carried out via a rotary transformer disposed in the rotary drum unit.
A method for connecting the magnetic heads and the rotary transformer via a conductive member is disclosed in, for example, Japanese Laid-open Patent Application No. Sho 59-119505 or Japanese Laid-open Utility Model Application No. Sho 63-149409. In such a method, two conductive members per magnetic head are secured to a holder having electrical insulating properties, and the holder is disposed between the magnetic heads and each conductive pattern of the rotary transformer.
In a more general method using no elastic member, electrical connection between the magnetic heads and the rotary transformer (rotor core) disposed in the upper cylinder has been provided by extending lead wires connected to a head base and lead wires of the rotary transformer (rotor core) onto a conductive circuit board mounted on the top face of the upper cylinder and connecting these lead wires on the conductive circuit board, as by soldering.
In such a rotary drum unit, however, since the lead wires are used to provide electrical connection between the magnetic heads and the rotary transformer, the lead wires must be connected at a large number of points. Specifically, there has been the problem that the operation of connecting the lead wires becomes complicated due to factors such as the requirements that the lead wires be connected to the head base; the lead wires from the head base be connected to the conductive circuit board; the lead wires from the rotary transformer be connected to the conductive circuit board; and so on.
Although the magnetic heads and the rotary transformer are disposed relatively close to each other within the upper cylinder, long lead wires must be used since the lead wires connected to both of them are led to the conductive circuit board provided on the upper cylinder. This leads to the problem that the cost of products increases.
An arrangement for solving the above-described problems is disclosed in the aforesaid Japanese Laid-open Patent Application No. Sho 59-119505, Japanese Laid-open Utility Model Application No. Sho 63-149409, and so on. FIG. 1 is an exploded perspective view diagrammatically showing a rotary magnetic head apparatus (corresponding to the rotary drum unit) according to one embodiment of the device set forth in Japanese Laid-open Utility Model Application No. Sho 63-149409.
The rotary drum unit 1 consists of a rotating upper drum 2 and a stationary lower drum 3. Head bases 5 each of which holds a magnetic head 4 are secured to the upper drum 2, and a head circuit board 7 is secured to each of the head bases 5. The head circuit board 7 has first conductive patterns 6a and 6b connected to the coil of the associated magnetic head 4.
A conductive circuit board 10 which has second conductive patterns 9a and 9b connected to a transformer coil is secured to a rotor core 8a of a rotary transformer 8.
Contacts 11a and 11b are respectively inserted into cutouts 13a and 13b formed in a holder 12. Each of the contacts 11a and 11b is made of an elastically deformable member which conducts electricity between opposed faces thereof. The holder 12 is secured to the head base 5 by the engagement between the head base 5 and engagement projections 14a, 14b and 14c. The upper drum 2 and the lower drum 3 are combined in such a manner that the contacts 11a and 11b are compressed and elastically deformed to enable electrical conduction, respectively, between the first conductive pattern 6a and the second conductive pattern 9a and between the first conductive pattern 6b and the second conductive pattern 9b.
However, the above-described conventional example has the following disadvantages since elastic material such as silicone rubber is used for the contacts 11a and 11b which serve as conductive members:
(1) It is difficult to reliably hold the conductive members (contacts) 11a and 11b on the holder 12, and they easily come off during assembly. PA1 (2) While the holder 12 combined with the conductive members 11a and 11b is being secured to the upper drum 2, each of the conductive members 11a and 11b is compressed in two directions and easily deformed. As a result, since the magnetic heads are not held in uniform contact with the conductive patterns 6a, 6b and 9a, 9b, conduction failure easily occurs. PA1 (3) As the number of magnetic heads to be mounted is increased, the number of conductive members increases accordingly, and the operation of securing the conductive members to the holder 12 and that of securing the holder 12 to the upper drum 2 become complicated. For the aforesaid reasons, imperfect products may be manufactured or the reliability of products may be impaired, with the result that high cost and numerous steps are required for quality control.